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Biomedical subjects

B Khan

Publications and source records attributed to B Khan.

At least 37 records · Page 2Linked to original sources
PubMed1996

Advantage of Inoue balloon catheter in mitral balloon valvotomy: experience with 220 consecutive patients.

Percutaneous mitral balloon valvotomy (PMV) using the Inoue balloon catheter was attempted in 220 consecutive patients with severe symptomatic mitral stenosis. Their age range was 10-63 mean 30 +/- 10 years; 161 patients were females and 59 were males; 29 patients were in atrial fibrillation. Eleven patients were pregnant; 14 patients underwent previous surgical commissurotomy. The procedure was technically successfully performed in 215 (97.7%) patients. The mean fluoroscopy time was 15.5 +/- 6.4 min and mean procedure time was 109 +/- 79 min. Optimal results (group I) was achieved in 207 patients who have mitral score of 7 +/- 1. PMV resulted in decrease in left atrial pressure from 23 +/- 5 to 14 +/- 4 mm Hg (P < 0.001), the mean mitral valve gradient (MVG) decreased from 15 +/- 4 to 6 +/- 3 mm Hg (P < 0.001). The mitral valve area (MVA) by catheter increased from 0.7 +/- 0.2 to 1.7 +/- 0.5 cm2 (P < 0.001) and MVA as determined by echocardiography (2DE) increased from 0.8 +/- 0.1 to 1.9 +/- 0.3 cm2 (P < 0.001). The results were suboptimal in eight patients who have a mitral score of 10 +/- 1 (group II) MVA by catheter increased from 0.7 +/- 0.2 to 1 +/- 0.1 cm2 and Doppler MVA increased from 0.8 +/- 0.1 to 1.3 +/- 0.1 cm2. There were no deaths or thromboembolism. Two patients developed cardiac tamponade; mild mitral regurgitation (MR) developed in 24 patients (11%) and increased by one grade in another 22 patients (10%). Severe MR was encountered in three patients (1.4%). A small ASD (QP/QS < or = 1.3) was detected by oximetry in 5% of patients and by color-flow mapping in 26% of patients. One hundred fifty-eight patients from group I were followed up, for a mean of 32 +/- 12 months; MVA remained at 1.7 +/- 0.4 cm2. Seven patients developed mitral restenosis in group I, and 5 out of 8 patients developed restenosis in group II. We conclude that the hemodynamic results are good and comparable with those reported with double balloon technique. However, the Inoue balloon has several advantages over the double balloon technique: (1) low incidence of mitral regurgitation and ASDs; (2) shorter procedure and fluoroscopy time; and (3) low complication rates and the valve anatomy affects the immediate and late outcome of mitral balloon valvotomy.

Adolescent↗
PubMed1996

Chest physiotherapy and post-extubation atelectasis in infants.

We investigated the role of chest physiotherapy (CPT) in preventing post-extubation atelectasis (PEA) in infants. Sixty-three infants who were admitted to the neonatal intensive care unit and intubated for more than 24 hours and who showed no evidence of atelectasis by chest x-ray prior to extubation were enrolled in the study. Infants were randomly assigned to 2-hourly CPT, 4-hourly CPT, or a no CPT group. Chest physiotherapy began immediately after extubation and consisted of postural drainage, bilateral chest vibration, and suctioning. A second chest x-ray was obtained on all infants 24 hours following extubation. The three groups were comparable in birth weight, gestational age, and duration of intubation. In the 24-hour period following extubation, the incidence of PEA was not statistically significant in the three groups (P = 0.33). Two infants in the 2-hourly CPT group were placed on nasal continuous positive airway pressure; two in each of the 2-hourly and the no CPT groups required re-intubation and intermittent positive pressure ventilation to treat symptomatic atelectasis. We conclude that post extubation chest physiotherapy as used in this study did not prevent atelectasis in extubated infants.

Drainage, Postural↗
PubMed1996

Prospective randomized trial comparing sequential avulsion with stripping of the long saphenous vein.

Eighty patients with primary varicose veins of the long saphenous system were randomized to have the long saphenous vein removed either by stripping to below the knee or by sequential avulsion. There was no difference between the two methods in the time taken to remove the vein. There was significantly more pain after stripping during the week following operation (P < 0.001). Median pain score after stripping was 5, reducing to 3 at 1 week, compared with 2, reducing to 1, for sequential avulsion. Median area of bruising measured at 1 week was 160 (range 0-1800) cm2 for stripping and 56 (range 0-544) cm2 for sequential avulsion (P < 0.01). Sequential avulsion is less painful, reduces bruising and avoids a significant scar below the knee.

Activities of Daily Living↗
PubMed1996

Immediate and long-term effect of mitral balloon valvotomy on severe pulmonary hypertension in patients with mitral stenosis.

The pulmonary vascular hemodynamics were studied in 21 patients with severe mitral stenosis and severe pulmonary hypertension. Hemodynamic data were obtained before and immediately after mitral balloon valvotomy (MBV) and at follow-up 7 to 14 months (mean 12 months) later by repeat catheterization. The mean pulmonary capillary wedge pressure (PCW) decreased from 27 +/- 5 to 15 +/- 4 mm Hg (p < 0.001). The mean mitral valve gradient (MVG) decreased from 18 +/- 4 to 6 +/- 2 mm Hg (p < 0.001). Mitral valve area (MVA) increased from 0.6 +/- 0.1 to 1.5 +/- 0.3 cm2 (p < 0.02). Cardiac index increased from 2.2 +/- 0.3 to 2.6 to 0.5 L/min/m2 (p < 0.02). The pulmonary artery systolic pressure decreased from 65 +/- 13 to 50 +/- 13 mm Hg (p < 0.001), and no significant change was seen in pulmonary vascular resistance (PVR) immediately after MBV from 461 +/- 149 to 401 +/- 227 dynes/sec/cm(-5) (p = 0.02). At follow-up the MVA increased from 1.5 +/- 0.3 to 1.7 +/- 0.3 cm2 (p < 0.02). Cardiac index increased further to 3 +/- 0.4 L/min/m2 (p < 0.02). MVG and PCW pressure remained the same. The pulmonary artery systolic pressure decreased further to 38 +/- 9 mm Hg (p < 0.02). PVR decreased significantly to 212 +/- 99 dynes/sec/cm(-5) (p < 0.02). We concluded that the pulmonary artery pressure decreased without normalizing immediately after MBV and normalized in patients with optimal results from mitral balloon valvotomy 7 to 14 months later. Insignificant change in PVR was seen immediately after MBV and markedly decreased or normalized at late follow-up in patients with optimal result from MBV.

Adolescent↗
PubMed1996

Immediate and long-term effect of mitral balloon valvotomy on left ventricular volume and systolic function in severe mitral stenosis.

To determine the immediate and long-term effect of mitral balloon valvotomy (MBV) on left ventricular (LV) volume and function, we studied 17 patients (mean age 27 +/- 9 years) with severe mitral stenosis undergoing MBV by cardiac catheterization and angiography before and immediately after MBV and at mean 12 months later. At baseline, LV end-diastolic volume index (EDVI) was reduced. Ten patients had EDVI < or = 55 ml/m2, and four patients (23.5%) had LV ejection fraction < 50%. EDVI increased from 60 +/- 17 ml/m2 to 66 +/- 17 ml/m2 (p < 0.05) immediately after MBV and increased further to 72 +/- 16 ml/m2 (p < 0.05) later. Stroke volume index increased from 34 +/- 10 ml/m2 to 41 +/- 12 ml/m2 (p < 0.05) immediately after MBV and increased further to 50 +/- 11 ml/m2 (p < 0.001) later. LV end diastolic pressure increased from 12 +/- 5 mm HG to 16 +/- 4 mm HG (p < 0.05) immediately after MBV and fell to 13 +/- Hg at follow-up. LV ejection fraction increased from 57 +/- 7% to 62 +/- 6% (p < 0.05) immediately after MBV and 71 +/- 8% later (p < 0.001). Mean systolic ejection rate increased from 82 +/- 35 ml/sec to 101 +/- 48 ml/sec (p < 0.05) immediately after and 165 +/- 81 ml/sec later (p < 0.05). Systemic vascular resistance fell from 1887 +/- 525 dyne/sec/cm-5 to 1280 +/- 231 dyne/sec/cm-5 (p < 0.001) at follow-up. We conclude that the LV end-diastolic volume and systolic function are reduced in patients with mitral stenosis, and the LV end-diastolic volume is increased immediately after MBV and continues to increase at follow-up 12 months later; the LV ejection performance improves after successful MBV because of an increase in end-diastolic LV volume (preload) and reduction of SVR.

Adolescent↗
PubMed1995

Antipyrine clearance and metabolite excretion in patients with chronic hepatitis C.

BACKGROUND/AIMS: Our aim was to study whether chronic hepatitis C affects the three metabolic pathways of the model drug antipyrine differently. METHODS: We measured antipyrine clearance from saliva as well as urinary excretion of its main metabolites 4-hydroxy-antipyrine, 3-hydroxy-methyl-antipyrine, and nor-antipyrine in 24 patients with chronic hepatitis C and in 21 healthy control subjects. Due to incomplete urine collection, 12 liver patients and three controls were excluded. RESULTS: Antipyrine clearance (mean +/- SD) was significantly lower in patients with chronic hepatitis C, 1.2 +/- 0.7 l.h-1 (n = 12), than in controls (n = 18), 2.2 +/- 1.0 l.h-1 (p = 0.006). The urinary excretion of each of the metabolites was depressed to an equal extent in liver patients. The severity of the liver disease, as assessed by Child Pugh score, serum albumin and bilirubin, correlated significantly with antipyrine clearance and urinary excretion of the metabolite 3-hydroxy-methyl-antipyrine. The hepatitis activity index (Knodell) correlated with 3-hydroxy-methyl-antipyrine and 4-hydroxy-antipyrine, only. CONCLUSIONS: Moderate-severe chronic hepatitis C does not seem to depress the three main metabolic pathways of antipyrine differently.

Adult↗
PubMed1995

Splenomegaly in Baringo District, Kenya, an area endemic for visceral leishmaniasis and malaria.

The relationship between splenomegaly and visceral leishmaniasis (VL) was investigated during a cross-sectional study in 2,941 individuals in Baringo District, Kenya, where both malaria and VL are endemic. Spleen size was correlated with presence of malaria parasites in thick blood films and with evidence of present or past Leishmania donovani infection as determined by serology and history. Marked splenomegaly (Hackett grade 3 or greater) significantly correlated with present or previous leishmanial infection (chi 2 = 53.5; p < 0.001) whereas moderate splenomegaly (Hackett grade 1 or 2) significantly correlated with malaria parasitaemia (chi 2 = 73.03; p < 0.001). The presence of antimalarial antibodies did not contribute to the differentiation of the cause of splenomegaly. The diagnostic significance of splenomegaly in this population is discussed.

Adolescent↗
PubMed1994

Mitral balloon valvotomy in children with Inoue balloon technique: immediate and intermediate-term result.

Percutaneous mitral balloon valvotomy (PMV) using the Inoue balloon technique was attempted in 170 patients. Of these, 30 patients were children aged 10 to 18 years (mean 15.9 +/- 2.7 years). There were 16 female and 14 male patients. All were in sinus rhythm. The procedure was successful in 28 patients (93%). PMV was performed using 20 to 28 mm (mean 25 mm) diameter balloon catheters with an echo-Doppler guided stepwise mitral dilation technique. After PMV, the mean left atrial pressure decreased from 25 +/- 5 to 14 +/- 4 mm Hg (p < 0.001). The mean mitral valve gradient (MVG) decreased from 16 +/- 4 to 6 +/- 3 mm Hg (p < 0.001). The mitral valve area (MVA) by catheter increased from 0.7 +/- 0.2 to 1.7 +/- 0.5 cm2 (p < 0.001), and MVA as determined by echocardiography (2DE) increased from 0.8 +/- 0.1 to 1.9 +/- 0.3 cm2 (p < 0.01). There were no deaths or thromboembolic complications; cardiac tamponade developed in one patient, mild mitral regurgitation (MR) developed in three patients (10%) and increased by one grade from (1+ to 2+) in another two patients (8%). A small atrial septal defect (ASD) assessed by color flow mapping developed in seven patients (25%); 90% were closed at 3 months. The Doppler and 2DE MVAs were maintained at 1.8 +/- 0.4 cm2 at 17 months' mean follow-up; one patient developed restenosis. We conclude the PMV using the Inoue balloon catheter is safe and effective in the treatment of severe mitral stenosis in children, with a low complication rate.

Adolescent↗
PubMed1994

Evidence for two single copy units in Theileria parva ribosomal RNA genes.

Bacteriophage clones containing ribosomal RNA genes of Theileria parva were isolated from genomic DNA libraries. Physical mapping studies revealed 2 ribosomal DNA units, which were distinguishable by restriction enzyme site polymorphisms in flanking sequences. The cloned ribosomal DNA units were mapped to 2 separate T. parva chromosomes. Analysis of sequences contained in lambda EMBL3 recombinants, together with Southern blot analysis of genomic DNA and data on the copy number of the rRNA genes, suggested that the rDNA units were not tandemly repeated. This organisation of ribosomal transcription units is similar to that described for other genera of apicomplexan protozoa, but 2 rDNA units, each containing single copies of the rRNA coding genes, would be the lowest copy number described for any eukaryote in which amplification of rRNA genes is not known to occur. EcoRI restriction fragment length polymorphisms, which were revealed using rRNA gene probes, separated T. parva stocks into 2 categories. Nucleotide sequence analysis of polymerase chain reaction-amplified internal transcribed spacer DNA revealed 2 different ITS sequences derived from rDNA transcription units within the genome of a cloned T. parva parasite. Polymorphism was also observed between ITS sequences amplified from the DNA of different T. parva stocks. A synthetic oligonucleotide derived from T. parva Uganda ribosomal ITS DNA sequences hybridised to DNA from the T. parva Uganda stock, but not to the DNA of the T. parva Muguga stock. This oligonucleotide is potentially useful as a marker for the T. parva Uganda stock.

Animals↗
PubMed1994

E-SHAP: an effective treatment in selected patients with relapsed non-Hodgkin's lymphoma.

BACKGROUND: The optimal treatment of relapsed or refractory non-Hodgkin's lymphoma is unknown. The reported encouraging results of a salvage regimen, E-SHAP (etoposide 40 mg/m2/day x 4, methyl prednisolone 500 mg daily x 4, cytosine arabinoside 2 gm/m2 one dose and cisplatinum 25 mg/m2/day x 4), at the M.D. Anderson Hospital in Texas, which resulted in a 65% response rate, could not be reproduced in the United Kingdom (0% response). PATIENTS AND METHODS: Twenty-six patients with relapsed (n = 16) or refractory (n = 10) non-Hodgkin's lymphoma were treated at our Centre by a modified E-SHAP regimen (cytosine arabinoside 1 gm/m2 one dose). The treatment was intended as remission induction before BMT (n = 16), as salvage by itself (n = 5) and for palliation of symptoms (n = 5). RESULTS: The overall response rate was 72% (CR = 7 and PR = 11). A comparison of Kaplan-Meier curves showed a statistically significant improvement in median relapse-free survival in patients who had previously achieved CR (p = 0.0012), no bulky disease (P = 0.0006) and no B-symptoms (P = 0.0004). The toxicity was acceptable: 8 instances of febrile neutropenia, 2 of reversible renal impairment and 2 symptomatic electrolyte abnormalities. No fatal toxicities were encountered. The median time to treatment failure was 191 days and median overall survival was 190 days. CONCLUSIONS: E-SHAP is an active combination chemotherapy when used as a salvage regimen or for remission induction before bone marrow transplantation in selected patients with relapsed non-Hodgkin's lymphoma. Patients who previously achieved CR, with low tumour burden and no B-symptoms are the best candidates for this treatment. It has a limited palliative effect.

Adolescent↗
PubMed1993

Cultivation of Plasmodium falciparum parasites in a serum-free medium.

The elimination of serum from Plasmodium falciparum culture media could decrease costs, enhance procurement, and improve the feasibility of large-scale production of parasite material. We provide a semi-defined, serum-free formulation, of commercially available constituents that supports P. falciparum parasite growth at rates comparable with those obtained with serum-supplemented media. The medium is composed of RPMI 1640 to which HEPES, extra glucose, bicarbonate, and hypoxanthine have been added. Bovine albumin and serum-derived, lipids-cholesterol-rich mixture are then used in place of serum.

Animals↗
PubMed1993

Single dose aprotinin in routine cardiac surgery.

Evidence exists that the serine protease inhibitor, aprotinin, when used in high dosage, can reduce the bleeding associated with cardiopulmonary bypass. This high dosage is particularly effective in patients at increased risk for bleeding. Less convincing information is available for regimens that use a lower dose and its place in routine cardiac surgery has not been fully resolved. Some studies have shown significant benefit from a single dose added to the cardio-pulmonary bypass prime and we re-examined this alternative. In a randomized, prospective, double-blinded study, we compared this single dose method with placebo in a low risk adults undergoing a first procedure. Benefit was considered established if a significant reduction in blood loss or the use of transfused blood products was seen. We found a significant reduction in red cell transfusion but no improvement in blood loss or blood component transfusion in the treated group. This included patients maintained on aspirin as well as those not receiving aspirin. Aspirin significantly increased blood loss in both control and treatment groups and the usage of blood products in the treatment group. Aprotinin in this low, single dosage was not confirmed as an effective means of improving hemostasis following CPB in routine cardiac surgery.

Adult↗
PubMed1993

Response of falciparum malaria to chloroquine and three second line antimalarial drugs in a Kenyan coastal school age population.

Ambulatory rural school children in the Mombasa area with P. falciparum parasitaemia were examined and randomly assigned to treatment with one of three second-line antimalarials--amodiaquine, pyrimethamine/sulphadoxine (P/SD) and pyrimethamine/sulfalene (P/SL). Clinical signs and parasitaemia were followed daily for the first week and on days 14 and 28. WHO Mark II schizont inhibition tests were performed for all the above 3 drugs and chloroquine. The total number of cases was 73. The mean parasite density was 142.1 +/- 207; 102.7 +/- 166; 82.74 +/- 93 parasites per 300 WBC for amodiaquine, P/SD, and P/SL, respectively. In vitro tests showed a chloroquine resistance rate of 60% and no resistance to all of the second line drugs. Also, all children treated successfully cleared their parasitaemia with mean clearance rates of 2.05 +/- 0.57; 1.86 +/- 0.47; 2.05 +/- 0.50 days for amodiaquine, P/SD and P/SL, respectively. Even though, no difference in the effectiveness between the second line drugs used was found, reinfection rates as depicted by day 28 parasitaemia differed--amodiaquine 16%; P/SD 0%; and P/SL4.35%. This difference could be attributed to the difference in the pharmacokinetic properties of the drugs.

Adolescent↗
PubMed1991

Plasmodium falciparum sensitivity to erythromycin and 4-aminoquinoline combinations in vitro.

Although erythromycin has been reported to be active against Plasmodium falciparum in vitro and P. berghei in vivo and in vitro when given alone or with chloroquine, it has been difficult to demonstrate a beneficial effect for the combination of erythromycin and chloroquine when used for the treatment of P. falciparum infections in humans. We developed a seven-day test of parasite sensitivity to a 4-aminoquinoline and erythromycin combination in vitro. Eight isolates of P. falciparum from the Kenyan coast were culture-adapted and exposed to erythromycin with chloroquine or with amodiaquine. The interaction of the drugs was evaluated by plotting the concentration of each drug needed to inhibit parasite growth. In seven isolates the combination of chloroquine and erythromycin was antagonistic; one isolate showed slight synergy The combination of amodiaquine and erythromycin was synergistic in three isolates but antagonistic in five. An antagonistic interaction may explain why erythromycin does not enhance chloroquine treatment of malaria in vivo in Kenya.

Aminoquinolines↗
PubMed1990

Identification of a high risk subgroup of patients with silent ischaemia after myocardial infarction: a group for early therapeutic revascularisation?

Asymptomatic ("silent") ischaemia has been shown to be of prognostic significance in patients with stable and unstable angina and more recently in patients recovering after myocardial infarction. No therapeutic regimen has yet been shown to improve the prognosis of patients with silent ischaemia after infarction, which can be found in as many as a third of these patients. Attempts to achieve therapeutic revascularisation in all these patients may be undesirable, but early revascularisation could be especially beneficial in some selected high risk patients. Two hundred and fifty consecutive clinically stable survivors of myocardial infarction who had predischarge submaximal exercise tests were followed up for a year. Silent ischaemia was found in 27% of these patients; 15% had symptomatic ischaemia. Patients with a positive exercise test were prescribed a beta blocker before discharge. Mortality in patients with silent (9.4%) and symptomatic (5.4%) ischaemia in the first year after infarction was not significantly different. Patients with symptomatic ischaemia were more likely to have undergone coronary artery bypass grafting in the first year. Patients with silent ischaemia were, however, significantly more likely to die than patients with a negative exercise test (relative odds 12:1). Patients with silent ischaemia and an abnormal blood pressure response or who could not complete a submaximal exercise protocol were at particularly high risk, being 32 times more likely to die than those with a negative test (95% confidence interval from 3.3 to 307 times more likely). First year mortality in this group was 22%. The benefits of therapeutic revascularisation in this high risk group need to be studied.

Coronary Angiography↗